Connecting rod and internal combustion engine and automotive vehicle incorporating the same

Abstract

A connecting rod made of a titanium alloy is a split-type connecting rod which includes a rod main body, and a big end located at an end of the rod main body, the big end being fracture-split into a rod portion which continues from the end of the rod main body and a cap portion which is coupled to the rod portion. The rod portion and the cap portion each have a fractured surface on which rugged features are present. A difference in height between a highest portion and a lowest portion on each fractured surface is about 230 μm or more.

1. A split connecting rod made of a titanium alloy, comprising:
 a rod main body; and 
 a big end located at an end of the rod main body, the big end having a throughhole; wherein, 
 the big end is fracture-split into a rod portion which continues from the end of the rod main body and a cap portion which is coupled to the rod portion; 
 the rod portion and the cap portion each have a fractured surface on which rugged features are present; 
 a difference in height between a highest portion and a lowest portion on each fractured surface is about 230 μm or more; 
 each of the rod portion and the cap portion has inclusions in an area around the fractured surface thereof; and 
 a longitudinal direction of the inclusions is at an angle of no less than 0° and no more than about 30° with respect to an abutting surface between the rod portion and the cap portion. 
 
   
   
     2. The connecting rod of  claim 1 , wherein the titanium alloy includes a rare-earth element and sulfur, and the inclusions are a compound of the rare-earth element and sulfur. 
   
   
     3. The connecting rod of  claim 2 , wherein the titanium alloy includes no less than about 0.05 wt % and no more than about 0.7 wt % of the rare-earth element and no less than about 0.05 wt % and no more than about 0.2 wt % of sulfur. 
   
   
     4. The connecting rod of  claim 1 , wherein the longitudinal direction of the inclusions is substantially parallel to the abutting surface. 
   
   
     5. The connecting rod of  claim 1 , wherein metal flow lines in an area around the abutting surface are substantially parallel to the longitudinal direction of the inclusions. 
   
   
     6. The connecting rod of  claim 1 , wherein the big end has a bolt hole in which a bolt for coupling together the rod portion and the cap portion is to be screwed, and
 the bolt hole is a bottomed hole which extends from the cap portion toward the rod portion and has a bottom surface within the rod portion. 
 
   
   
     7. The connecting rod of  claim 6 , wherein a shortest distance from the bottom surface of the bolt hole to an outer surface of the rod portion is about 3 mm or more. 
   
   
     8. The connecting rod of  claim 6 , wherein the rod portion of the big end includes a protrusion which protrudes toward the small end. 
   
   
     9. An internal combustion engine comprising the connecting rod of  claim 1 . 
   
   
     10. An automotive vehicle comprising the internal combustion engine of  claim 9 .